The effect of mannitol on renal function after cardiopulmonary bypass in patients with preoperative renal dysfunction

Abstract

Renal dysfunction and failure after cardiopulmonary bypass have a significant influence on postoperative morbidity and mortality. Mannitol has been widely used to preserve renal function during bypass, although there is little evidence of its efficacy. We recruited 38 patients, not on dialysis, undergoing routine cardiac surgery and who had blood creatinine concentration 130–250 μmol.l−1. Patients were anaesthetised with 10 μg.kg−1 fentanyl and 3–4 mg.kg−1.h−1 propofol. All patients received aprotinin according to the Hammersmith regimen. The bypass circuit was primed with 1000 ml Hartmann's solution, 500 ml succinyl-linked gelatine and 5000 iu heparin. In a double-blinded study, patients were randomly allocated to receive 0.5 g.kg−1 mannitol in the bypass prime or the equivalent volume of Hartmann's solution. Peroperative fluid management was standardised. Creatinine, urea and sodium concentrations, and daily fluid intake and output, were recorded daily from the day of surgery until the third postoperative day. Statistical analysis was by ANOVA. We recruited 17 patients to the mannitol group and 21 patients to the control group. There were no significant differences between the groups in urea, creatinine or sodium concentrations, or in urine output in the perioperative period (Fig. 1). Daily urine output in patients undergoing cardiopulmonary bypass either with (left-hand bar of each pair) or without (right-hand bar) mannitol. As is the case for patients with normal renal function, mannitol in the bypass prime does not appear to preserve renal function in those with established pre-operative renal dysfunction [1].